Using shower pump to boost bath pressure

muir_steve

I have installed a new bath recently withthe typ of tap which can be installed anywhere with the filler spout separately. I have a gavity fed system but the pressure is very low.

The bath plumbing is 22mm pipe and I reduced it to 15mm to connect to the taps, this shouldn't make any diference as the connection between the taps and the filler is 15mm flexi anyway the filler spout is quite large though.

The water pressure has always been poor to the shower and i am going to install a power pump, can I use a pump underthe bath to boost the pressureto the bath taps or use a pump to power both shower and bath (the shower is tee'd off the bath plumbing anyway).

Alan_M_2

The only way you could use a single pump in this set up is to use a thermostatic shower valve with inbuilt diverter to switch between the tap and shower.

The problem with running a tap solely off a pump is it can be operated in the fully cold or fully hot positions and the pumps absulotesly must have water running through them at all times, so half a pump running dry (either the hot or cold side) will destroy the pump very quickly.

Alternatively you'll have to install a pump suitable fo the tap design (these have a name which escapes me at the moment). Single impellor I think - but do check that.

The problem has arisen not because you have low pressure, but because you've bought a tap designed for a high pressure system, anything other than a 3/4" fitting to a bath tap is high pressure. (or higher than we have in the UK generally).

p4u1_2

I would agree with Alam M, anything but a 3/4" (22mm) for a bath in the UK will not be suitable unless of course you have a rather unusual setup. Assuming you have a cold water tank in the loft feeding both the hot and cold water in the bathroom (hot water via the hot water tank in the airing cupboard), then you must use 22mm pipe all the way and avoid flexible hoses, and isolating valves that are NOT the full flow type. Flexible hoses are often fitted with isolation valves that reduce the diameter of the pipe to little more than 10mm, 15mm at the very most.

beefster

Alan_M wrote:

The only way you could use a single pump in this set up is to use a thermostatic shower valve with inbuilt diverter to switch between the tap and shower.

The problem with running a tap solely off a pump is it can be operated in the fully cold or fully hot positions and the pumps absulotesly must have water running through them at all times, so half a pump running dry (either the hot or cold side) will destroy the pump very quickly.

Alternatively you'll have to install a pump suitable fo the tap design (these have a name which escapes me at the moment). Single impellor I think - but do check that.

The problem has arisen not because you have low pressure, but because you've bought a tap designed for a high pressure system, anything other than a 3/4" fitting to a bath tap is high pressure. (or higher than we have in the UK generally).

Out of interest.......
Re the pump used for the taps. Whats the differance between this and a shower? You can still run a shower on 100% cold?? It would seem logical that a shower pump would be ok in this situation as the controls are virtually the same as a shower mixer? ie a range of temps from 100% hot to 100% cold?

The pump wont run dry unless the tank empties. The water temp in the side of the pump with the water shut off will raise due to the heat generated by the pump itself and there being no through flow of water.......so i can understand that as a problem but would have thought this was part of the design?
just interested?!

Alan_M_2

A thermostatic shower will always allow some hot through even if it's turned fully cold so this keeps the pump lubricated, of course a non thermostatic shower wouldn't but it's bad practice to pump a non thermostatic shower so the problem shouldn't arise.

The pumps specially devised for taps can run the hot and cold impellors seperately (as I understand it - don't take this as gospel) so avoiding unnecessary stress on the shaft bearings (which are the bits that generally fail).

Boohbah

I used to suffer from very low water pressure in the upstairs bathroom, so
I've located a pump beneath the bath which services the bath basin loo bidet & shower.
Works a treat know.

http://www.stuart-turner.co.uk/products/products.htm

muir_steve

Thanks guys, i'll have a look at that site and see if i can find anything, failing that i'll just have to change the taps.